4,4,4-Trifluorobutane-2-one is useful as a solvent, detergent and as a versatile building block for pharmaceutical products. International Patent Publication No. 2002-03959 discloses 4,4,4-trifluorobutane-2-one as an ingredient of aerosol pharmaceutical products. Also, 4,4,4-trifluorobutane-2-one is disclosed in Journal of Fluorine Chemistry (1987), 36, 163-170, as an intermediate product for optically-active amino acid derivatives. It is expected to be used in various other fields.
The Journal of Organic Chemistry (1983), 48(8), P. 1370, discloses a method for producing 4,4,4-trifluorobutane-2-one by electrolysis of a mixture of sodium trifluoro acetate and isopropenylacetate in aqueous acetone. This method needs a complicated apparatus for carrying out the electrolysis process. Tetrahedron Letters (1992), 33(10), P.1291, discloses a method for producing 4,4,4-trifluorobutane-2-one by reacting an enol ester represented by CH2═C(OAc)CH3 or CH2═C(OCOCH3)CH3, with sodium trifluoromethanesulfonate and t-butyl hydroperoxide in the presence of a Cu(II) catalyst. Japanese Non-examined Patent Publication No. 10-109954 discloses that a fluorine containing ketone, as represented by CnHmF2n+1−mCOCH3 where “n” represents an integer number of 2 to 4, and “m” represents 0 or 1, can be prepared by reacting a fluoroalkyl carboxylic acid of CnHmF2n+1−mCOOH with methyl magnesium bromide in an ether solvent.
These conventional methods may be suitable for laboratory scale synthesis of 4,4,4-trifluorobutane-2-one, but are not easily scaled up for large and industrial manufacture.
It is also known that fluoroolefins subjected to acid hydrolysis may form a fluorine containing ketone (Synthesis, (5), 1986, p. 355, Tetrahedron Letters (1986), 27(9), 1027-1030). However, a fluoroolefin having a structure of C═CF is not always converted into a ketone, as disclosed by Tetrahedron Letters (1986), 27(9), 1027-1030. In this respect, the inventors of the present invention have also confirmed that even if fluoroolefins are contacted with water in the presence of a proton acid, the fluoroolefins do not always proceed with an expected reaction.
On the other hand, Alty et al. invented novel fluorobutene derivatives and a novel method for producing such compounds. The invention of Alty et al. was filed as an International Application No. PCT/US2004/013029, which was assigned to the same assignee of the present invention, and which is incorporated by reference herein. Prior to the invention of Alty et al., it was known that halogenated alkanes subjected to thermal dehydrofluorination affords olefins, but that such thermal dehydrofluorination processes are not practical, especially on an industrial scale because of a low conversion rate and a poor selectivity.
Since the carbon-fluorine bond is very strong, the energy for cleaving the carbon-fluorine is very close to that necessary for cleaving a carbon-carbon bond. In general, the temperature necessary for releasing hydrogen fluoride (HF) from a fluorine compound is far higher than that necessary for releasing hydrogen chloride (HCl) from an analogous chlorinated compound containing a chlorine atom at the same site instead of a fluorine atom. Such a high temperature for the dehydrofluorination causes decomposition and rearrangement, thereby reducing the selectivity of the objective synthesis. U.S. Pat. No. 2,480,560 discloses that a dehydrofluorination process of five distinct hydrofluorocarbons in the absence of a catalyst gives fluoroolefins at a low selectivity.
On the other hand, it is known that a catalyst can reduce the temperature of the dehydrofluorination, and is expected to improve the selectivity and to avoid decomposition and rearrangement. U.S. Pat. No. 2,599,631 describes a method for producing vinyl fluorides by dehydrofluorination of 1,1-difluoroethane either in a thermal process (no catalyst), or in a catalytic process, and discloses that the catalytic process is more useful. However, a catalyst is easily deactivated after a short time by products formed during the dehydrofluorination process.
It is also known that dehydrofluorination of a fluorine-containing substrate with base can afford fluoroolefins. However, dehydrofluorination processes using base generally give isomers that are different from products obtained by a thermal dehydrofluorination process, and therefore it may be difficult to efficiently produce desired fluoroolefins.